Creation of a dormer and addition of a Velux roof window to an existing loft conversion

Appeal Decision Site visit made on 7 May 2025 by Alexander O’Doherty LLB (Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 27 May 2025 Appeal Ref: 6000083 Honeysuckle House, 2 Mill Lane, Downe, Orpington BR6 7HP • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Andrew Hinds against the decision of the Council of the London Borough of Bromley. • The application Ref is DC/23/03887/FULL6. • The development proposed is described on the application form as, “Creation of a dormer and addition of a Velux roof window to an existing loft conversion”. Decision 1. The appeal is dismissed. Main Issues 2. The main issues are: • whether the proposed development would be inappropriate development in the Green Belt, having regard to the National Planning Policy Framework (the Framework) and any relevant development plan policies; • the effect of the proposed development on the openness and purposes of the Green Belt; • the effect of the proposed development on the character and appearance of the area; and • whether any harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations, so as to amount to the very special circumstances required to justify the proposed development. Reasons Whether Inappropriate Development 3. The appeal site comprises Honeysuckle House, a detached 2-storey dwelling located on a corner plot at the junction of Mill Lane and North End Lane in a verdant residential area. A detached garage is present opposite the access to the site. 4. Paragraph 154 of the Framework establishes that development in the Green Belt is inappropriate unless certain exceptions apply. The main parties have focussed on paragraph 154 c) of the Framework which relates to the extension or alteration of a building provided that it does not result in disproportionate additions over-and- above the size of the original building. Appeal Decision 6000083 2 5. Part a of Policy 51 of the Bromley Local Plan (adopted 2019) (Local Plan) provides that, amongst other things, extensions or alterations to dwellinghouses in the Green Belt will only be permitted if the net increase in the floor area over that of the original dwellinghouse is no more than 10%, as ascertained by external measurement. The Inspector in appeal decision Ref APP/G5180/D/24/3340032 found that this policy is more prescriptive than the Framework (which does not provide a definition of ‘disproportionate additions’), and that the assessment under paragraph 154 c) cannot be solely based on a statistical set of indicators. I concur with the Inspector’s reasoning in these respects. 6. Mention has been made of the visual impact of the proposed development on the openness of the Green Belt, that front dormers are present on other nearby properties, and the effect of the proposed development on the appearance of Honeysuckle House and the wider landscape. However, paragraph 154 c) refers to the size of the original building, and accordingly that is the primary focus of my assessment under this main issue. 7. Honeysuckle House originally had a floor area of approximately 120 square metres. A loft conversion was previously undertaken. As paragraph 154 c) refers to the size of the original building, I concur with the findings of the Inspector in appeal decision Ref APP/G5180/D/24/3340032 that, in assessing any floorspace increase, it would be reasonable to exclude the original floorspace of the loft as this forms part of the original dwelling. As such, the original floor area for the purposes of my assessment under paragraph 154 c) is approximately 160 square metres. 8. Honeysuckle House has previously been extended via the addition of a single storey porch, with a floor area of approximately 6 square metres, and a 2-storey extension with a floor area of approximately of 27 square metres. 9. Paragraph 154 c) can include structures which are physically detached from the building of which they are an extension. In this case, the garage on site is situated a short distance from Honeysuckle House, and appears to be used for purposes incidental to the enjoyment of Honeysuckle House. Therefore, for the purposes of paragraph 154 c), the garage is an extension of Honeysuckle House. The Council have stated that the garage has a floor area of approximately 45 square metres, and this figure has not been disputed by the appellant. As such, the original building has a floor area of approximately 238 square metres. 10. The proposed development would add approximately 4 square metres in floor area, resulting in an increase of approximately 82 square metres over-and-above the size of the original building (approximately 51%). Whilst the proposed development itself would be modest in terms of its floor area, the total uplift in size over-and-above the original building would clearly be substantial. Considering this, and as the volume and external dimensions of the original building have already been significantly increased over-and-above its original state (excluding the loft conversion), the proposed development would result in disproportionate additions over-and-above the size of the original building. 11. Hence, even though the requirements of part a of Policy 51 of the Local Plan are only afforded moderate weight in undertaking this assessment, the proposed development would not benefit from the exception to inappropriate development provided at paragraph 154 c) of the Framework. Appeal Decision 6000083 3 12. The proposed development would therefore constitute inappropriate development in the Green Belt. Inappropriate development is, by definition, harmful to the Green Belt. Openness & purposes of the Green Belt 13. The Planning Practice Guidance (PPG) advises that openness is capable of having both spatial and visual aspects1. Honeysuckle House benefits from a small dormer on its north-facing roof slope. In combination, the proposed 2 dormer extensions would be much larger than this existing dormer, thereby reducing the openness of the Green Belt in spatial terms. The proposed development would cover a considerable proportion of the roof slope. Due to this, and the protrusion of the 2 dormers from the roof slope, the proposed development would reduce the openness of the Green Belt in visual terms, although this impact on openness would be somewhat mitigated by the presence of dormers on Pine Cottage, a dwelling which is situated on an adjacent plot to the site. 14. As the site is well-concealed from the surrounding landscape and is not in an open or a rural area, and the site is positioned at a lower level than development to the east and the south, these adverse impacts would be confined to the local area. Nevertheless, the proposed development would result in harm to the openness of the Green Belt, meaning that it would undermine its purpose in terms of its assistance in safeguarding the countryside from encroachment. Character and appearance 15. Honeysuckle House is situated on a corner plot, and accordingly occupies a prominent position in the street scene in this residential area. Although, due to the topography of the area, the site is situated lower than development to the east of the site, its northern roof slope is visible for some distance along Mill Lane, including from near the entrance to Snodland Close. 16. As the Inspector noted in appeal decision Ref APP/G5180/D/24/3340032, Standard Road comprises an eclectic mix of housing types and architectural design, where there is no consistent pattern of development within the street scene. In contrast to the street scene of Standard Road, I observed that although there are a variety of property types in the vicinity of the site, and Pine Cottage has previously been extended with dormer extensions, dormer extensions are not common on buildings on Mill Lane, Snodland Close, and North End Lane. Additionally, many of the buildings on these 3 streets have a legible, uncluttered, and understated appearance. The design of Honeysuckle House reflects these characteristics. 17. The proposed 2 dormer extensions would rise up to the ridge line of the roof of which they would form a part, albeit the roof would be set-back. They would be linked by a recessed central section, and as such in combination the proposed 2 dormer extensions would have a large width and height relative to the roof as a whole. Although the proposed development would represent the same form of development as the dormers present on Pine Cottage and its materials and windows would match those existing, such that it would not appear wholly incongruent in the street scene, its coverage across a significant proportion of the roof and its protrusion from it would mean that it would appear in the street scene 1 Paragraph 64-013-20250225 Appeal Decision 6000083 4 as a bulky addition to Honeysuckle House. As a result, the uncluttered and understated appearance of Honeysuckle House would be undermined. 18. As overly-dominant features in clear view in the street scene, the fact that the proposed 2 dormer extensions would be situated lower than the main ridge height of Honeysuckle House would not off-set the adverse impacts identified. Considering Honeysuckle House’s prominent position in the street scene, these adverse impacts would compromise the character of the area. 19. The design of Pine Cottage differs significantly from Honeysuckle House, as would the proposed 2 dormer extensions in comparison with those on Pine Cottage. So, the presence of the dormers on Pine Cottage would not alter the resulting negative visual impacts of the proposed development. Given the differences between the street scene as seen from near the site and that at Standard Road, referred to above, the presence of 1 Standard Road as extended in the local area does not alter my findings above. 20. I therefore find that the proposed development would have an unacceptable and harmful effect on the character and appearance of the area. It would conflict with part c of Policy 6 of the Local Plan which provides that, amongst other things, the design and layout of proposals for the alteration or enlargement of residential properties should ensure that dormer windows should be of a size and design appropriate to the roofscape and sited away from prominent roof pitches, unless dormers are a feature of the area. 21. The proposed development would conflict with parts a and b of Policy 37 of the Local Plan which provides that, amongst other things, developments will be expected to be imaginative and attractive to look at, of a good architectural quality and should complement the scale, proportion, form, layout and materials of adjacent buildings and areas, and positively contribute to the existing street scene. 22. The proposed development would also conflict with paragraph 135 c) of the Framework which provides that, amongst other things, planning decisions should ensure that developments are sympathetic to local character and history, including the surrounding built environment and landscape setting, while not preventing or discouraging appropriate innovation or change (such as increased densities). Other Considerations 23. The Framework makes it clear at paragraph 153 that substantial weight is given to any harm to the Green Belt, including harm to its openness. It establishes that 'very special circumstances' will not exist unless the potential harm to the Green Belt by reason of inappropriateness, and any other harm resulting from the proposed development, is clearly outweighed by other considerations. 24. The proposed development would enhance the living accommodation available at Honeysuckle House, including with respect to the floor-to-ceiling height and light into the existing room. However, these benefits would be largely private in nature. The proposed development would likely provide economic benefits to the local area arising from the work provided for construction professionals, but it has not been demonstrated that any economic benefits would be significant. Little weight is given to these matters in support of the proposed development. Appeal Decision 6000083 5 Other Matters 25. The proposed development represents a revised scheme. However, this factor alone is a neutral matter, which does not weigh in favour of the proposed development. The conduct of the Council during the processing of the planning application is not a matter that I can assess in the context of a planning appeal. Balancing of Considerations 26. The proposed development would be inappropriate development in the Green Belt and would result in a reduction in its openness. These matters carry substantial weight. Moreover, planning harm would arise due to the proposed development’s unacceptable and harmful effect on the character and appearance of the area. In this regard, the Framework provides that the creation of high quality places is fundamental to what the planning and development process should achieve. Moderate weight has been given to this non-Green Belt harm. 27. Taking account of the little weight given to the other considerations, they do not clearly outweigh the totality of the harms identified. The very special circumstances required to justify the proposed development do not exist. The proposed development would conflict with Policy 49 of the Local Plan which provides that, amongst other things, within the Green Belt permission will not be given for inappropriate development unless very special circumstances can be demonstrated that clearly outweigh the harm by reason of inappropriateness or any other harm, and with part a of Policy 51 of the Local Plan, summarised above. The proposed development would also conflict with the aims of Green Belt policy as set out in the Framework. Conclusion 28. For the reasons given above, having considered the development plan as a whole, the approach in the Framework, and all other relevant material considerations, I conclude that the appeal should be dismissed. Alexander O’Doherty INSPECTOR